50+ Software Engineer Level 1 Interview Questions and Answers

The program reads a file and selects the first 3 lines. It then identifies the longest line and counts the number of words in that line.

• Read the file using appropriate file handling methods

• Store the first 3 lines in an array of strings

• Iterate through the array to find the longest line

• Count the number of words in the longest line using string manipulation methods

O(nk) is better than O(n) for large data and hash tables.

• O(nk) is better because it takes into account the size of the data and the number of keys.

• For large data and hash tables, the size of n will be large, making O(nk) more efficient.

• O(n) assumes a constant number of keys, which may not be the case in practice.

• Amazon may have chosen O(nk) for better scalability and performance.

Amazon displays only a subset of search results based on various factors like relevance, popularity, and user preferences.

• Amazon uses algorithms to determine which products to display in search results.

• Factors considered include product relevance, customer reviews, sales rank, and availability.

• Machine learning techniques may be used to personalize search results based on user behavior and preferences.

• Amazon also considers factors like seller reputation and fulfillment options...read more

The question is about finding the shortest path in a 3x3 matrix with weighted edges.

• This is a graph traversal problem.

• Use a graph algorithm like Dijkstra's algorithm or A* search to find the shortest path.

• Assign weights to the edges and calculate the sum of weights for each possible path.

• Choose the path with the smallest sum of weights as the shortest path.

The product will be the key and the brands will be the values.

• The key in this case refers to the unique identifier for each product.

• The values are the different brands associated with each product.

• For example, if the product is a smartphone, the key could be the model number and the values could be the different brands that manufacture that model.

Hash tables are a data structure that uses a hash function to map keys to values, providing efficient lookup, insertion, and deletion.

• Hash tables use a hash function to convert keys into array indices.

• They provide constant-time average case complexity for search, insert, and delete operations.

• Collisions can occur when different keys map to the same index, which can be resolved using techniques like chaining or open addressing.

• Examples of hash table implementations include Pyt...read more

The Fibonacci series can be applied in day-to-day life for various purposes.

• Financial planning: Fibonacci numbers can be used to calculate investment growth and determine optimal investment strategies.

• Architecture and design: Fibonacci ratios can be used to create aesthetically pleasing designs and layouts.

• Nature and biology: Fibonacci patterns can be observed in the growth of plants, arrangement of leaves, and formation of shells.

• Music and art: Fibonacci sequences can be use...read more

Intersection of two linked lists is finding the common node(s) between them.

• Traverse both lists simultaneously and compare each node to find the intersection point.

• Use a hash set to store nodes of one list and check for intersection in the other list.

• Optimize by finding the lengths of both lists and aligning the pointers before comparison.

React is a JavaScript library for building user interfaces. NPM is a package manager for JavaScript.

• React is used for creating interactive UI components

• NPM is used for managing dependencies and packages in JavaScript projects

• I used React in my project for its component-based architecture and virtual DOM efficiency

• I used NPM in my project to easily install and manage third-party libraries and tools

Creating a Spring Boot backend service from scratch involves setting up database connection, creating entities, repositories, services, controllers, and handling client requests.

• Set up database connection in application.properties file

• Create entity classes representing database tables

• Create repository interfaces extending JpaRepository for database operations

• Create service classes to implement business logic

• Create controller classes to handle client requests and map them to a...read more

Use binary search to find the key in a sorted and rotated array.

• Apply binary search to efficiently find the key in the array.

• Check if the key is in the left or right half of the array based on the mid element.

• Adjust the search space accordingly based on the comparison of key with elements at start, mid, and end of the array.

Radix sort has a running time of O(nk), where n is the number of elements and k is the length of the longest element.

• Radix sort is a non-comparative sorting algorithm that sorts elements by their individual digits or characters.

• It works by distributing the elements into 10 buckets based on the value of the least significant digit, then repeatedly redistributing them based on the next significant digit.

• The process continues until all digits have been considered, resulting in a...read more

Find the maximum area rectangle with all boundaries as 1 in a matrix of 0 and 1.

• Use dynamic programming to calculate the maximum area rectangle.

• Iterate through each row of the matrix and calculate the maximum area rectangle with that row as the base.

• Keep track of the maximum area rectangle seen so far.

• Time complexity: O(n^2), where n is the number of rows in the matrix.

Java is statically typed, object-oriented language with a focus on performance and scalability. Python is dynamically typed, high-level language known for its simplicity and readability.

• Java is statically typed, meaning variable types are explicitly declared at compile time. Python is dynamically typed, allowing for more flexibility but potentially leading to runtime errors.

• Java is more verbose and requires more boilerplate code compared to Python, which emphasizes readabilit...read more

Program to check if a string can be rearranged to form a palindrome

• Create a frequency map of characters in the string

• Count the number of characters with odd frequencies

• If there is at most one character with odd frequency, the string can be rearranged to form a palindrome

Use a subquery to find the 2nd largest number in a database table.

• Use a subquery to select all distinct numbers from the table

• Order the numbers in descending order

• Use LIMIT 1,1 to select the second row which will be the 2nd largest number

Storage class specifiers in C define the scope and lifetime of variables.

• auto - default storage class for local variables

• extern - used to declare a global variable in another file

• static - retains the value of a variable between function calls

• register - suggests to the compiler to store the variable in a register for faster access

I have intermediate level experience in programming with Java, Python, and C++.

• I have worked on projects involving data structures and algorithms.

• I have experience with object-oriented programming and design patterns.

• I have developed web applications using frameworks like Spring and Django.

• I have also worked on projects involving machine learning and natural language processing.

• I am comfortable working with databases and have experience with SQL and NoSQL databases.

Find the longest alternating sequence of increasing, decreasing, and increasing numbers.

• Iterate through the array and keep track of the current sequence length and direction.

• If the direction changes, update the sequence length and reset the direction.

• Return the longest sequence length found.

• Example: [1, 2, 3, 2, 1, 2, 3, 4, 3, 2, 1] returns 7 (1, 2, 3, 2, 1, 2, 3).

Memory optimisation can be achieved by reducing memory usage, improving data structures, and implementing efficient algorithms.

• Use data structures that require less memory, such as arrays instead of lists

• Avoid memory leaks by properly managing memory allocation and deallocation

• Implement caching mechanisms to reduce the need for frequent memory access

• Optimise algorithms to reduce unnecessary memory usage, such as using dynamic programming

Diamond problem in Java occurs when a class inherits from two classes that have a common ancestor, resulting in ambiguity.

• Occurs in multiple inheritance when a class inherits from two classes that have a common ancestor

• Results in ambiguity as the compiler cannot determine which method to call

• Can be resolved using interfaces or by explicitly overriding methods

Program to find length of string using custom function

• Create a custom function that takes an array of strings as input

• Iterate through each string in the array and calculate its length

• Return the lengths of all strings in an array

Inheritance is a concept in object-oriented programming where a class inherits attributes and methods from another class.

• Types of inheritance: single inheritance, multiple inheritance, multilevel inheritance, hierarchical inheritance

• Examples: Animal class can be inherited by Dog and Cat classes, Vehicle class can be inherited by Car and Bike classes

To find the sum of consecutive numbers in a circular linked list, iterate through the list and keep track of the sum.

• Iterate through the circular linked list starting from a given node

• Keep track of the sum of consecutive numbers as you traverse the list

• Handle the case when the list loops back to the starting node

SQL Joins are used to combine data from multiple tables. There are four types of SQL statements: SELECT, INSERT, UPDATE, and DELETE.

• SQL Joins are used to combine data from two or more tables based on a related column between them.

• The four types of SQL statements are SELECT, INSERT, UPDATE, and DELETE.

• SELECT is used to retrieve data from one or more tables.

• INSERT is used to add new data to a table.

• UPDATE is used to modify existing data in a table.

• DELETE is used to remove data ...read more

A program to determine if a number is even or odd.

• Use the modulo operator (%) to check if a number is divisible by 2.

• If the remainder is 0, the number is even. Otherwise, it is odd.

• Example: 4 % 2 = 0 (even), 5 % 2 = 1 (odd)

HTTP methods are used to indicate the desired action to be performed on a resource.

• GET - Retrieve data from a server

• POST - Submit data to a server

• PUT - Update an existing resource on a server

• DELETE - Remove a resource from a server

• PATCH - Partially update a resource on a server

• OPTIONS - Get information about the communication options available for a resource

Python supports various data types including integers, floats, strings, lists, tuples, dictionaries, and more.

• Integers: whole numbers without decimal points (e.g. 5, -3)

• Floats: numbers with decimal points (e.g. 3.14, -0.5)

• Strings: sequences of characters enclosed in quotes (e.g. 'hello', '123')

• Lists: ordered collections of items (e.g. [1, 'apple', True])

• Tuples: ordered, immutable collections of items (e.g. (1, 'banana', False))

• Dictionaries: unordered collections of key-value ...read more

Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity.

• Normalization is used to eliminate data redundancy by dividing the database into multiple tables and defining relationships between them.

• It helps in reducing data anomalies such as insertion, update, and deletion anomalies.

• Normalization is achieved through a series of stages called normal forms (1NF, 2NF, 3NF, BCNF, etc.).

• For example, in a database of students and cou...read more

Multithreading allows multiple threads to run concurrently within a single process, improving performance and responsiveness.

• Multithreading allows for parallel execution of tasks within a single process.

• Threads share the same memory space, allowing for efficient communication and data sharing.

• Thread management is handled by the operating system, which schedules threads for execution.

• Examples of multithreading include web servers handling multiple client requests simultaneousl...read more

The right view of a tree shows the rightmost node at each level, while the bottom view shows the bottommost node at each horizontal distance.

• To find the right view, perform a level order traversal and keep track of the rightmost node at each level.

• To find the bottom view, perform a vertical order traversal and keep track of the bottommost node at each horizontal distance.

• Both views can be represented as arrays of strings, where each string represents the value of a node.

OOP is a programming paradigm based on the concept of objects, which can contain data in the form of fields and code in the form of procedures.

• OOP focuses on creating objects that interact with each other to solve problems.

• Key concepts include encapsulation, inheritance, and polymorphism.

• Encapsulation involves bundling data and methods that operate on the data into a single unit.

• Inheritance allows classes to inherit attributes and methods from other classes.

• Polymorphism allow...read more

An empty class in Java is a class that does not have any member variables or methods.

• An empty class can be defined like this: class EmptyClass {}

• Empty classes are often used as placeholders or markers in code.

• Even though an empty class does not have any explicit members, it still inherits from the Object class in Java.

Polymorphism is the ability of a single function or method to operate on different types of data.

• Polymorphism allows objects of different classes to be treated as objects of a common superclass.

• There are two types of polymorphism: compile-time (method overloading) and runtime (method overriding).

• Example of compile-time polymorphism: function overloading where multiple functions have the same name but different parameters.

• Example of runtime polymorphism: method overriding wher...read more

Code in C to reverse an array of strings

• Use two pointers, one pointing to the start of the array and the other pointing to the end

• Swap the elements at the two pointers and move them towards each other until they meet in the middle

Implement a function to reverse a string

• Create a new empty string to store the reversed string

• Iterate through the original string from the end to the beginning and append each character to the new string

• Return the new reversed string

BFS travel of binary tree

• BFS stands for Breadth First Search

• It is a traversal algorithm for trees and graphs

• In BFS, we visit all the nodes at the same level before moving to the next level

• We use a queue data structure to implement BFS

• Example: BFS traversal of a binary tree with root node A would be A, B, C, D, E, F, G, H, I

The minimum number of runways required depends on the number of aircrafts and their arrival and departure times.

• Consider the number of aircrafts that will be arriving and departing at the same time.

• Calculate the maximum number of aircrafts that will be on the ground at any given time.

• Each aircraft requires a separate runway for landing and takeoff.

• The minimum number of runways required is equal to the maximum number of aircrafts on the ground at any given time.

Book reader system implementation

• Design a user interface for browsing and selecting books

• Implement a database to store book information and user data

• Develop a feature for bookmarking and saving progress

• Include options for adjusting font size and background color

• Integrate with payment system for purchasing books

Find the maximum sum of a path in a matrix from top left to bottom right corner.

• Use dynamic programming to calculate the maximum sum of a path ending at each cell.

• The maximum sum of a path ending at cell (i,j) is the maximum of the maximum sums of paths ending at (i-1,j) and (i,j-1), plus the value of cell (i,j).

• The maximum sum of a path from top left to bottom right corner is the maximum sum of a path ending at the bottom right corner.

• Time complexity: O(n^2), space complexit...read more

Object-oriented programming concepts that focus on data abstraction, encapsulation, inheritance, and polymorphism.

• Abstraction: Hiding complex implementation details and showing only necessary features.

• Encapsulation: Binding data and methods that operate on the data into a single unit.

• Inheritance: Creating new classes from existing classes to reuse code and extend functionality.

• Polymorphism: Objects of different classes can be treated as objects of a common superclass.

• Example:...read more

Rotate a 2D matrix by 180 degrees in place without using extra space.

• Iterate through the matrix and swap elements symmetrically across the center row.

• Use two pointers, one starting from the first row and the other from the last row, to swap elements.

• Repeat the swapping process for each row until the entire matrix is rotated.

• Example: Input matrix = [[1,2,3],[4,5,6],[7,8,9]], Output matrix = [[9,8,7],[6,5,4],[3,2,1]]

Multithreading is the ability of a CPU to execute multiple threads concurrently, allowing for improved performance and responsiveness.

• Multithreading allows multiple tasks to be executed simultaneously on a single CPU core.

• Each thread has its own program counter, stack, and set of registers.

• Example: A web browser using multithreading to load a webpage while simultaneously downloading images in the background.

SQL query to retrieve data from a database and sorting algorithm to organize the data

• Use SELECT statement in SQL to retrieve data from a specific table

• Use ORDER BY clause in SQL to sort the retrieved data based on a specific column

• Implement a sorting algorithm like Bubble Sort, Quick Sort, or Merge Sort in a programming language to organize data

Expected CTC for Software Engineer Level 1 depends on company, location, experience, and negotiation skills.

• Expected CTC can vary based on company policies and budget.

• Location plays a significant role in determining CTC due to cost of living differences.

• Experience level can impact the salary offered, with more experienced candidates typically receiving higher CTC.

• Negotiation skills can also influence the final CTC offered by the company.

• For example, a Software Engineer Level ...read more

Find the length of the longest increasing subsequence in an array.

• Use dynamic programming to solve the problem efficiently.

• Maintain an array to store the length of longest increasing subsequence ending at each index.

• Traverse the array and update the array for each index.

• Return the maximum value in the array as the length of the longest increasing subsequence.

Reverse a linked list using recursion

• Create a recursive function to reverse the linked list

• Pass the head of the linked list to the function

• Base case: if the current node is null, return null

• Recursive case: reverse the rest of the list and point the next node's next to the current node